In numerous situations there today exists a need for the cleaning and conditioning of biological and dental implant surfaces. However, currently available methods not always result in a satisfactory result and/or have problems with damaging of tissues or the use of toxic or otherwise harmful agents.
Medical implants are frequently implanted into vertebrate animals today to replace anatomy and/or restore any function of the body.
Dental implants are utilized in dental restoration procedures in patients having lost one or more of their teeth. A dental implant comprises a dental fixture, which is utilized as an artificial tooth root replacement. Thus, the dental fixture serves as a root for a new tooth. The dental fixture is typically a screw, i.e. it has the shape of a screw. The screw is surgically implanted into the jawbone, where after the bone tissue grows around the screw and the screw is fixated in the bone with the bone in direct contact with the implant surface. This process is called osseointegration, because osteoblasts grow on and into the surface of the implanted screw. By means of the osseointegration, a rigid installation of the screw is obtained.
Dental implants are often made of a metal material. Today, all available dental implants on the market are made of titanium, titanium-zirconium or zirconiumoxide/ceramics. Other examples of metal materials commonly utilized for constructing metallic medical implants are steel, titanium, zirconium, tantalum, niobium, hafnium and alloys thereof. In particular, titanium and titanium alloys have proved to be suitable to utilize for constructing dental and other implants. This is due to the fact that titanium is biocompatible, it has excellent corrosion resistance in body fluids, it resists adherence of bacteria, and it is light and strong. Also, titanium shows very good osseointegration behaviour.
Once the dental implant screw is firmly anchored in the jawbone, it may be elongated by attachment of an abutment to the screw. The abutment may, just as the screw, be made of titanium, a titanium alloy, zirconium or a zirconium alloy. The shape and size of the utilized abutment are adjusted such that it precisely reaches up through the mucosa after attachment to the screw. A dental restoration such as a crown, bridge or denture may then be attached to the abutment. Alternatively, the implant screw has such a shape and size that it reaches up through the mucosa after implantation, whereby no abutment is needed and a dental restoration such as a crown, bridge or denture may be attached directly to the screw.
Periodontal diseases are caused by bacteria and toxins in dental plaque, which is a sticky colourless film constantly forming on the surfaces of the teeth. These diseases are very common; it has been estimated that they affect as much as between 70-90% of the world population, and they are the major cause of tooth loss in people over 35 years of age. The most common forms of periodontal disease are gingivitis and periodontitis.
Periodontal disease is, second to tooth decay, the most frequent oral disease and may lead to partial or complete tooth loss. It is caused by bacterial deposits accumulating on tooth surfaces along the gingival margins and results in destruction of tooth-supporting tissues. The destruction of tooth-supporting tissues results in a deepening of the space (periodontal pocket) between the root of the tooth and the gum tissue.
Gingivitis is the mildest form of periodontal disease, causing the gingiva to become red, swollen, and bleed easily. Gingivitis, if untreated, may develop into periodontitis. In periodontitis the infection has progressed to involve the oral tissues which retain the teeth in the jawbone. If untreated, periodontitis ultimately leads to loss of the affected tooth.
Chronic periodontitis, the most frequently occurring form of periodontitis, results in inflammation within the supporting tissues of the teeth, progressive loss of attachment as well as progressive alveolar bone resorption. This form of periodontitis is characterized by pocket formation and/or recession of the gingiva. As the destruction advances, the mobility and movement of teeth increase finally causing spontaneous loss of a tooth or a necessity of tooth extraction.
In patients with implants, periodontitis may develop into a condition called perio-implantitis and is caused by the colonization of bacteria of the implants's surface. The infection may be caused by bacteria introduced during surgery or post-surgically by insufficient oral hygiene. Inflammation in the bone surrounding the implant then causes loss of bone which ultimately may lead to failure of the implant.
Patients with implants are also susceptible of developing a condition called periimplant mucositis. This condition involves the presence of inflammation in the mucosa at an implant but with no signs of loss of supporting bone in contrast to the observed bone loss in periimplantitis patients.
Treatment of periodontal disease usually involves the removal of bacterial deposits and dental calculus. This is commonly performed by scraping the teeth to remove bacterial deposits and dental calculus, including deposits in the gingival margin. However, it is difficult to have full access for treating deeper periodontal pockets resulting in remaining bacteria that may re-infect the tissue. This is of course also the case for other bacterially infected tissues, where an incomplete removal of bacteria or dead or damaged tissue may cause problems for healing and e.g. re-infection. Therefore, this treatment is often combined with surgical procedures to open the tooth pocket to expose the tooth. The roots are then mechanically freed from bacterial deposits and calculus but also granulation tissue and bacterial toxin removal.
It is often advantageous or necessary to debride surgically exposed hard tissue surfaces. For example, debriding of surgically exposed hard tissue surfaces may be advantageous or necessary to perform before regenerative treatment, i.e. in order to prepare the hard tissue surfaces for regenerative treatment. Examples of conditions, which may be associated with a treatment in which debridement of a surgically exposed hard tissue surface is advantageous or necessary to perform in order to prepare the surface for regenerative treatment, are: periimplantitis, periodontitis lesions, marginal periodontitis, apical periodontitis, furcation defects, apical granulomas and cysts, bone cysts, bone tumours, bone granulomas, bone cancers, (infected) extraction sockets, alveolitis sicca (“dry socket”), cleaning of apicectomy defects, localized osteomyelitis, trauma induced defects, resection or revision of implants, resection or revision of fractures, and removal of temporary bone implants.
As mentioned above, peri-implantitis is commonly treated by surgery. Options include debridement, rinsing of the affected tissue and treatment with antibiotics.
It is a well-known fact that the morbidity and frequency of adverse effects, such as e.g. post-surgery effects, are directly related to, and often proportional to, the time used for the debridement of surgically exposed hard tissue surfaces. Thus, rapid debridement treatment ensures a better total treatment outcome. In addition, the total treatment outcome may also depend on the degree of damaging of the anatomical structure by the debridement tool during the debridement procedure. Furthermore, the total treatment outcome may also depend on the amount of contaminating material residues that is left on the treated surface by the debridement tool. Contaminating material residues may trigger a foreign body response.
The surface of dental implants, or the vicinity thereof, has sometimes to be cleaned after placing. This is particularly important when an infection or contamination occurs, causing periimplantitis. In these cases the surface of the ailing implant has to be cleaned from microbes and contaminants to stop the progression of the disease and ensure reintegration of the implant. Failure to clean the implant surface will eventually lead to loss of bone and implant, and make further alternative treatments difficult and sometimes even impossible.
Traditionally, the dentists and surgeons utilize cleaning tools that are relatively hard, i.e. they have a high hardness degree, in order to provide a thorough cleaning of the metallic medical implant during e.g. surgery, implantation or other treatments. Such hard cleaning tools may, for example, be made of stainless steel, hard metal alloys or hard polymers. However, such hard cleaning tools are not suitable to utilize for cleaning all metallic implant materials. For example, they are not suitable to utilize for cleaning medical implants of soft metals or metal alloys, such as e.g. titanium, a titanium alloy, zirconium or a zirconium alloy. This is due to the fact that such medical implants have a delicate surface that may be damaged when contacted by hard cleaning tools. Thus, when hard cleaning tools are utilized for cleaning a medical implant of, for example, titanium, a titanium alloy, zirconium or a zirconium alloy there is a great risk that the surface of the medical implant is damaged by the cleaning process. Then the surface structure of the medical implant is negatively affected. In addition, any produced scratches in the medical implant surface may constitute sites in which bacteria may adhere, which may result in re-infections in the tissue surrounding the medical implant, e.g. the gingiva.
Furthermore, the above mentioned hard cleaning tools may contaminate a delicate surface of a medical implant when utilized for cleaning the medical implant surface, i.e. they may leave contaminating material residues on the medical implant surface. These material residues often trigger a foreign body response and are generally not well accepted by the human body. Also, it is difficult to clean a surface completely with a curette and non-cleaned spots will always remain (see e.g. Schwarz et al., Clin. Oral Invest. (2005) 9: 111-117).
In order to avoid the above mentioned damaging risk, a cleaning tool in the form of a brush comprising soft bristles may be utilized instead of the above mentioned hard cleaning tools for cleaning metallic medical implants having delicate surfaces. The soft bristles may then be made of e.g. a plastic material, nylon or any other synthetic fibers. One example of such a brush for cleaning a dental implant is disclosed in U.S. Pat. No. 6,345,406. However, the cleaning effect of such brushes on the medical implant surface is not as good as that of hard cleaning tools, i.e. it is easier to clean more efficiently and thoroughly by means of hard cleaning tools. In addition, in case such a brush is utilized for cleaning a medical implant surface, it is common that one or more soft bristles, or parts thereof, come loose from the brush and get stuck in the surrounding tissue, e.g. mucosa, whereby inflammation or infections often results.
Etching during periodontal surgery is performed with three main aims: removal of bacterial toxins, removal of smear layer and exposure of collagenous fibres in the root surface and increase visibility through hemostatic effects.
Of these, the two first have been evaluated in vitro employing mainly citric acid and to some extent ortho-phosphoric acid both of which operate at a pH of around 1 (Lowenguth R A, Blieden T M. Periodontal regeneration: root surface demineralization. Periodontology 2000 1993; 1:54).
Scaling and root planing are performed to remove bacterial deposits, calculus and the superficial layers of the root surface (cementum and dentin), structures and tissues which harbour bacterial toxins. Such toxins are not only confined to the bacterial deposits but are also found adsorbed to periodontally diseased root surfaces. These substances have been shown to inhibit cell attachment in vitro, a function necessary for healing. Thus, the aim of scaling and root planing is to provide a biologically acceptable surface for marginal healing. However, following root surface instrumentation, areas of contaminated cementum, as well as a smear layer covering the instrumented surfaces may still remain. Additional root surface treatment, such as etching has been reported to remove the smear layer.
Application of etching agents has been reported to remove smear and debris which may result from scaling and root planing. However, it also may affect the mineralized root surface.
Since its inception citric and ortho-phosphoric acid etching (pH 1) of root surfaces have been reported to result in new attachment or reattachment. In vivo studies have indicated that connective tissue healing with some reparative cementum formation will result after such treatment. There is also reason to believe that application of citric or ortho-phosphoric acid to a periodontal wound during surgery will increase visibility through hemostatic effects as well as facilitate removal of granulation tissue.
As is evident from the above, the cleaning of biological and implant surfaces are difficult and the available mechanical and chemical methods have problems. In conclusion, there is also a need for a cleaning device, which is hard enough to clean/debride well without damaging hard or soft tissue surfaces, which does not leave contaminants on an exposed tissue surface such that a foreign body response is triggered and which may be utilized for relatively rapid cleaning of a soft or hard tissue surface. In addition, there is still a need for improved methods for conditioning the surfaces of hard and soft tissue, and also for the conditioning of medical implant surfaces.